TargetScan 8 examines 6 types of canonical sites, as shown in this example for miR-1. These sites have contiguous pairing (blue) to the miRNA seed (red), and some include an additional match to miRNA nucleotide 8 or an A opposite miRNA nucleotide 1 (B represents C, G, or U; D represents A, G, or U).

Figure 1A from McGeary, Lin et al., 2019.